I've been lurking for a while and have seen quite a lot of comments about badly worded survey questions on sex/gender.
This is all down to the guidance provided by the research governing body, the Market Research Society. Researchers who fail to follow this guidance are open to investigation and disciplinary action.
www.mrs.org.uk/pdf/Guidance%20on%20Collecting%20Data%20on%20Sex%20and%20Gender.pdf
You can see from the sources listed at the end of the document that the guidance the MRS has given its members is based on government reports, which in turn, were influenced by the likes of GIRES, TELI, S Whittle et al.
I really recommend reading the Trans Data Position Paper by ONS (2009), which is the last one listed